Connections

• Device connects between existing battery control switch and existing boat power main.

• Additional connection to ignition 12 vdc positive and to negative ground.

 

Working Description

A positive size 0 battery cable (1) from the existing battery switch (2) output connects to the line side of the main relay (R-1). A connection from the line side of the main relay supplies positive 12 vdc via a fused 3 ampere supply (4) to a Pico relay (5) that is wired in a normally closed configuration.  In the closed mode power is passed to the wireless receiver (6). This receiver controls a polarity reversing momentary 12 vdc circuit that feeds the main latching relay coil (7). In operation, dependent on the polarity supplied by the wireless control relay, the main latching relay moves between open and closed positions. The load side (8) of the relay (R-1) is connected to the boat’s power main. A 12vdc positive connection from the ignition(s) (9) to the coil of the Pico relay (5) causes the Pico relay to open, thus interrupting the current to the wireless receiver relay (6). This prevents accidental disconnection of the boat’s power supply if the engine(s) is running. A negative common ground (10) ties the Pico relay (5) and the wireless receiver (6) to the boat’s negative ground. A manual over-ride switch (11) is connected from the line side to the load side of the main relay by size 1/0 cables to allow for manual bypass of the wireless control in the event of a failure of any part of the control system. The entire device is enclosed in a sealed weatherproof box with liquid tight stain relief fittings for all wires that penetrate the enclosure rendering it safe for wet locations or explosive environments.

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When the boat’s existing battery disconnect switch (2) is in the off position all current to the wireless switch is also disconnected and the device is non-functional. When the boat’s existing battery switch (2) is on the wireless receiver (6) is activated and listens for a Key FOB command. In listen mode the receiver consumes less than 10 nano amperes of current. When in momentary switching mode the receiver relay (R-1) consumes approximately 1.0 amperes of current, continuous coil current is 2.7 amp. No current is required to maintain the latching relay (R-1) in either the open or closed position. The Pico relay (5) is energized while the ignition is on and power is supplied during this time by the engine alternator supply.

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Utilizing Peukert’s law, the current drain of 10 nanoampes estimated on a conservative one battery, group 27 lead acid flooded with a 100 AHr rating at full charge of 12.6 v, would discharge the battery below 10.6 volts in 26 weeks in “listen” mode. Passive or normal discharge rates for typical lead acid batteries, for the above battery, would be approximately 4% per week or 4 amps per week. To reach an 80% charge level would then take 5 weeks for passive self-discharge. Acknowledge that most boats have multiple batteries or banks that would significantly increase this “listen” discharge time. These calculations would indicate the device has minimal effect on battery discharge time.

 

Improvements to the State of the Art

• Remote controlled battery disconnect switches already exist.

• Wireless remote controlled battery disconnect switches already exist.

• Remote controlled battery disconnect switches with manual over-rides already exist.

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The primary improvement to the state of the art is to incorporate an ignition sense circuit to prevent accidental power disconnection from an inadvertent activation of a wireless control. This enhancement of the totality creates an inherently safer solution for the application intended.